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Oltre il pianoforte e i conservatori: Il ruolo di Liszt nella fondazione di scuole (Ginevra, Roma, Budapest) il suo insegnamento della composizione
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Large-Eddy-Simulation framework for two-phase flows with heat transfer: Application to a two-dimensional jet in cross-flow
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Experimental study on triaxial fatigue properties of mudstone interlayers in CAES under synergistic effects of stress amplitude and time interval
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Soil organic matter decomposition in semi-arid mangrove stands (New Caledonia)
No full textInternational audienceOrganic matter (OM) dynamics in mangrove forests have been studied extensively in terms of the capacity of their soils to store organic carbon. While δ13C, δ15N, and C/N values for mangrove soils and sources are well reported, other indicators of OM maturity and composition are lacking. In this study, soil OM decomposition processes were investigated for a semi-arid bay head mangrove forest in New Caledonia. Mangrove tissues and 20-cm soil cores were collected in monospecific stands of Avicennia marina and Rhizophora stylosa. The isotopic compositions of the samples were assessed, along with their molecular compositions (lignin-derived phenols and neutral carbohydrates). Rock-Eval analysis was also performed on the samples to investigate OM characteristics. Results showed that stable isotope ratios and Rock-Eval parameters followed similar vertical trends beneath both species indicating the influence of depth on OM state. However, the more anoxic conditions beneath R. stylosa limited OM decomposition as shown by the lower TpS2 values (indicator of OM thermal stability). Neutral carbohydrates and, surprisingly, lignin-derived phenols, were lost at higher rates than bulk organic carbon beneath both mangrove species. Selective degradation of individual compounds was observed, and species-dependent variations associated with the redox conditions and the OM sources were identified. We suggest that lignin was degraded, even in anoxic environments, because of the amount of labile lignocellulosic components in the soil. These findings enhance our understanding of OM dynamics in mangrove ecosystems, shedding light on the mechanisms underlying carbon cycling and their implications for global carbon storage and ecosystem management
Biological effects of chlorogenic acid nanoformulations on colorectal cancer cells
No full textInternational audienceThe nanoencapsulation of chlorogenic acid (CGA) by nanospray drying was investigated as a protective bioactive delivery strategy. This study aimed to develop CGA-loaded nanoparticles (NPs) for potential application in colorectal cancer (CRC) therapy using the SW480 and HT-29 cell lines. Eight formulations were prepared with biopolymers—maltodextrin (MD), arabic gum (AG), starch (S), carboxymethyl cellulose (CMC), and hydroxypropyl methylcellulose (HPMC)—and the surfactant polysorbate 80 (PS80). The formulations were transformed into fine powders through nanospray drying and comprehensively characterized using physicochemical techniques. In vitro cytotoxicity and proliferation assays were performed using the MTT method across CGA concentrations from 0 to 400 µM. In addition, cell cycle analysis was performed by flow cytometry in HT-29 cells treated with formulations F1 (MD:CGA, 2:1) and F3 (AG:CGA, 2:1). Systems based on MD, AG, and S yielded spherical, smooth particles with an average diameter of about 360 nm, whereas those based on CMC and HPMC produced smaller particles of about 251 nm, likely due to lower polymer concentrations. Unloaded NPs exhibited low overall cytotoxicity in both SW480 and HT-29 CRC cell lines, confirming their biocompatibility. In contrast, CGA-loaded formulations induced a greater reduction in cell viability and proliferation, particularly in HT-29 cells. Cell cycle analysis revealed a slight increase in the sub-G1 population, with F1 promoting S-phase accumulation and F3 causing G2/M arrest. Among all formulations, those containing GA demonstrated significantly enhanced anticancer activity in CRC cells compared with free CGA. This effect appears to be cytostatic rather than apoptotic, suggesting a promising direction for further exploration
Assessing radiofrequency safety of active implants by measuring induced radiofrequency currents using MRI
No full textInternational audiencePurpose: During MRI in the presence of active wire-like implants, such as deep brain stimulation leads, there is a risk of thermal lesions in tissues adjacent to implant contacts due to radiofrequency currents induced in the wire. Currently, there is no established method to evaluate the radiofrequency (RF) safety of an implant in situ, due to complex interactions between the implant and the electric field inside the patient during MRI. This article presents a method to quantify the RF current in an implant using MRI acquisitions at very low SAR.Theory and Methods: To measure RF current in situ, a modified B1-mapping sequence is proposed to image the associated perturbation of the B + 1 field. A forward signal model links the RF current intensity to the MRI signal and is used to fit the RF current from acquired data. Electromagnetic simulations and experiments on a homogeneous phantom are presented for simplified and real implant wires to validate the method.Results: The presented model can correctly reconstruct RF current amplitudes from field maps obtained with detailed electromagnetic simulations, with a normalized RMS error of 4.7%. Phantom experiments show a good linearity between the square of the current measured by MRI and temperature increase (R 2 > 0.91), demonstrating that the RF current measurements quantitatively represent the effective heating.Conclusion: A method has been developed to quantify the RF current in situ from MRI signals. This method enables to predict the individual heating risk for other MRI sequences performed in the same scanning session
Dynamique de l'aimantation de sphères creuses d'hexaferrite de baryum
No full textInternational audienceThe hollow magnetic particles are versatile nanostructures promising for future spin-based technologies. The case of submicrometersized hollow spherical particles with a large uniaxial magnetic anisotropy is considered in this Chapter. By means of micromagnetic simulations, the equilibrium magnetization configuration and the associated linear response in the microwave range are investigated. Depending on the shell thickness and the external particle diameter, multiple resonant excitations are revealed and identified as spatially nonuniform magnetic modes. The changes induced by the presence of a medial planar domain wall for larger hollow spheres are analyzed with a focus on the magnetic excitations localized within the domain walls. The main experimental routes for fabricating 138hollow magnetic spheres are then presented and the emergent applications are highlighted
Truncated PNA-functionalized porous silicon biosensor for low-cost and early detection of troponin T in myocardial infarction
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A New C2-symmetric {SBI}-type zirconocene complex incorporating electron-donating substituents for highly productive, highly isoselective homo- and copolymerization of propylene
No full textInternational audienceThe new Me2Si-bridged bis(indenyl) proligand {Me2Si(2-Me-4-(3',5'-tBu(2)-4'-OMe-C6H2)-5-OMe-6-tBu-Ind)(2)}H-2 (1), incorporating bulky and electron-donating substituents both on the indene platform and the 4-aryl-indenyl moiety, was prepared. The corresponding C-2-symmetric ansa-zirconocene complex rac-{Me2Si(2-Me-4-(3',5'-tBu(2)-4'-OMe-C6H2)-5-OMe-6-tBu-Ind)(2)}ZrCl2 (1-ZrCl2) was synthesized and isolated in pure racemic form, and characterized by NMR spectroscopy, mass spectrometry and X-ray crystallography. The zirconocene complex, once activated with MAO in toluene solution, exhibited propylene polymerization activities at 60 degrees C up to 217,000 kg(PP).mol(Zr)(-1).h(-1), affording highly isotactic polypropylene (iPP) with [m](4) up to >99 mol % and T-m up to 160.1 degrees C. Also, the SiO2-MAO-supported metallocene complex (supp-1-ZrCl2) was evaluated in slurry bulk propylene polymerization at 70 degrees C, producing iPP with [m](4) content of 99.4-99.5 mol % and low amounts of regiodefects (0.4-0.5 mol %) (T-m up to 159.4 degrees C), with productivities up to 980,000 kg(PP)<middle dot>mol(Zr)(-1)<middle dot>h(-1). Also, polymerization of propylene in the presence of ethylene under slurry conditions allowed obtaining isotactic-rich iPP-co-E copolymers with very high activities up to 3,420,000 kg(PP)<middle dot>mol(Zr)(-1)<middle dot>h(-1). The new materials contained ca. 1 wt % of the incorporated ethylene units and featured melting transitions up to 147.5 degrees C